96 



INJURIOUS AND BENEFICIAL INSECTS OP CALIFORNIA. 



Life History. — The life history of this species is very imperfectly 

 known. The eggs, laid upon the trees the previous fall, hatch in the 

 spring, about blossoming 

 time (February and 

 .March), and the young 

 lice at once begin to at- 

 tack the young leaves and 

 fruit. The work upon 

 the leaves is similar to 

 that of the green apple 

 aphis, but causing them 

 to curl more and to turn 

 yellow. The work upon 

 the fruit is even more de- 

 st ructive, causing deform- 

 ity and non-maturity. In 

 most of the apple-growing 

 sections of the State the 

 attacks of this aphis have 

 been exceedingly severe. 

 About June the species 

 leaves the fruit trees and 

 migrates to unknown host 

 plants, and does not re- 

 turn until fall, in time 

 to give birth to true sex- 

 ual forms, the females of 

 which produce the over-wintering eggs. As in the case of green apple 

 aphis, many successive and overlapping broods occur each year. 



Nature of Work.— The curling of the leaves on the terminal shoots 

 and the stunting of the fruit, which is severely attacked, are character- 

 istic of the work of this louse. 



Distribution.— This species is widely distributed in practically 

 every apple-growing section of the State. 



Food Plants.— The rosy apple aphis attacks mainly the foliage and 

 young fruit of the apple, but it also works upon the hawthorn, white 

 thorn and mountain ash. 



Fig. 77. — Apples disfigxired by the attacks of the 

 rosy apple aphis when the fruit was young. These 

 were picked at harvest time. Reduced one half. 

 (Original) 



THE BLACK CHERRY APHIS 



Myzus cerasi (Fabricius) 



(Aphis cerasi Fabricius) 



(Fig. 78) 



Description.— The stem-mothers which hatch from the over-winter- 

 ing eggs are first dark brown, but gradually change to shining black 

 when fully matured. The bodies are somewhat pyriform, the antenna? 

 half as long as the body and dusky brown. The legs are also dusky 

 brown. The cornicles are one fourth as long as the body, cylindrical 

 and black. Until about the middle of July all of the lice are wing- 

 less. At this time winged migrants begin to appear. The succeeding 

 broods differ little from the first stem-mothers. The legs are pale 

 with apical half of femora, tips of tibia? and tarsi dark. The antenna? 



